.Wait() 与 GetAwaiter().GetResult() 之间有什么区别？

Question

My method returns Task . I want to wait until it finished. What should I use .Wait() or .GetAwaiter().GetResult() ? What is the difference between them?

Answer 1

Both are a synchronous wait for the result of the operation (and you should avoid those if possible).

The difference is mainly in handling exceptions. With Wait , the exception stack trace is unaltered and represents the actual stack at the time of the exception, so if you have a piece of code that runs on a thread-pool thread, you'd have a stack like

ThreadPoolThread.RunTask
YourCode.SomeWork

On the other hand, .GetAwaiter().GetResult() will rework the stack trace to take all the asynchronous context into account, ignoring that some parts of the code execute on the UI thread, and some on a ThreadPool thread, and some are simply asynchronous I/O. So your stack trace will reflect a synchronous-like step through your code :

TheSyncMethodThatWaitsForTheAsyncMethod
YourCode.SomeAsyncMethod
SomeAsync
YourCode.SomeWork

This tends to make exception stack traces a lot more useful, to say the least. You can see where YourCode.SomeWork was called in the context of your application , rather than "the physical way it was run".

An example of how this works is in the reference source (non-contractual, of course).

Answer 2

Try your best to avoid synchronously blocking on an asynchronous task.

In those rare exceptional cases, GetAwaiter().GetResult() will preserve the task exceptions,

If you use Wait it will throw AggregateException.

Refer to @stephen-cleary 's blog post 'a-tour-of-task-part-6-results'